The present invention relates to a process for the preparation of aliphatic primary sulfamates. The sulfamates which can be prepared by the present process may be represented by the formula: ##STR1## WHEREIN N IS AN INTEGER FROM 0-8 AND X and Y are hydrogen, provided that when n is 1, X and Y are either hydrogen, lower alkyl having 1-3 carbon atoms, aryl such as phenyl or arylalkyl such as benzyl, phenethyl and the like.
The aliphatic primary sulfamates of the present invention are prepared by reacting an alkanediol with a substituted sulfamoyl halide such as a substituted sulfamoyl chloride, for example, in a suitable solvent in the presence of a strong base. Suitable alkanediols which may be employed include 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,10-decanediol and the like. As the halide reactant, a substituted sulfamoyl halide is employed wherein the substituent is a protecting group which can be readily removed under acid conditions. Suitable groups which may be employed include groups such as t-butyl, benzyl, .alpha.-alkyl benzyl wherein the alkyl group has 1-3 carbon atoms, allyl and 1-alkyl-allyl wherein the alkyl group has 1-3 carbon atoms. The substituent on the sulfamoyl halide reactant is removed by treating the compound obtained from the reaction mixture with a strong acid. Acids such as trichloroacetic acid, trifluoroacetic acid, methanesulfonic acid, conc. sulfuric acid and conc. hydrochloric acid, for example, may be employed. The preparation of unsubstituted sulfamoyl halides involves steps which are inherently hazardous. The use of a substituted sulfamoyl halide in place of an unsubstituted sulfamoyl halide avoids the hazards associated with the preparation of sulfamoyl halides. Substituted sulfamoyl halides are prepared by reacting an appropriate amine such as, for example, t-butylamine or benzylamine, with a sulfuryl halide in a suitable solvent, such as acetonitrile, for example. Bases such as sodium hydride, potassium t-butoxide, potassium hydride, tributyltin, sodium amide and sodium are examples of bases which may be employed for the initial reaction. Suitable solvents for the reaction include toluene, benzene, xylene, ether, tetrahydrofuran, diglyme, 1,2-dimethoxyethane and p-dioxane.
The reaction with the substituted sulfamoyl halide may be carried out at room temperature, but it is preferred to carry out the reaction at a temperature between room temperature and about 60.degree. C. The removal of the protecting group is preferably carried out at room temperature in an inert atmosphere such as nitrogen, for example. The product is obtained from the reaction mixture by techniques known to those skilled in the art.
The aliphatic primary sulfamates, which are the subject of this invention, are useful in the control of fertility in male animals. The compounds are capable of interfering with sperm as they sojourn in the epididymis and thus bring about what is known as functional sterility, i.e., the gametes remain morphologically normal and show motility but normal fertilization is not achieved. Generally dosage levels of from about 5-200 mg./kg. are effective in inducing functional sterility. The preferred dosage range is from about 10-150 mg/kg. In addition to causing functional sterility of epididymal sperm, the primary sulfamates have antiandrogenic properties as manifested by inhibition of the size of the ventral prostate.
The general procedure followed to determine the activity of compounds which inhibit male fertility by altering the functional capacity of epididymal sperm is as follows:
A two week dosing period (i.e, the approximate period required for sperm transport through the epididymis) enables the separation of those drugs which affect epididymal sperm maturation and/or function from the antispermatogenic agents which have a longer delay in the onset of sterility. Each individual test involves 5 male rats (250-300 g.) caged together in air conditioned animal quarters and maintained on laboratory chow and tap water ad libitum. The compound to be tested is dissolved or suspended in appropriate vehicles (usually methylcellulose) and administered daily (usually i.g.) for 14 consecutive days. Control animals receive the vehicle only. At the end of the 14th day of treatment each male is individually caged with a proestrus female. Vaginal smears are checked the following morning for evidence of positive mating, and those males failing to mate are recohabited with proestrus females the following night. Males are sacrificed and autopsied the day after cohabitation for a gross examination of testes, epididymides, and accessory sex organs. Tissue samples of these organs are preserved for histological processing if observation yields a possible effect. Feamles (regardless of sperm presence in the vaginal washings) are autopsied 14 days after cohabitation to examine for pregnancy.
The inability of females to produce a viable embryo following a successful mating with treated males (two weeks of medication) is used as a measure of functional infertility. The number of males mating of those cohabited gives a gross indication of the drug's effect on libido. The size of the accessory sex organs provides an indication of the effect on androgen production. Microscopic analysis of epididymal sperm provides information on sperm quality (motility and morphology) and quantity.
The following examples describe the invention in greater particularity and are intended to be a way of illustrating and not limiting the invention.